Fan-out light-emitting diode (led) device substrate with embedded backplane, lighting system and method of manufacture

ABSTRACT

Panels of LED arrays and LED lighting systems are described. A panel includes a substrate having a top and a bottom surface. Multiple backplanes are embedded in the substrate, each having a top and a bottom surface. Multiple first electrically conductive structures extend at least from the top surface of each of the backplanes to the top surface of the substrate. Each of multiple LED arrays is electrically coupled to at least some of the first conductive structures. Multiple second conductive structures extend from each of the backplanes to at least the bottom surface of the substrate. At least some of the second electrically conductive structures are coupled to at least some of the first electrically conductive structures via the backplane. A thermal conductive structure is in contact with the bottom surface of each of the backplanes and extends to at least the bottom surface of the substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a of U.S. patent application Ser. No. 16/831,378,filed Mar. 26, 2020, which claims the benefit of U.S. ProvisionalApplication No. 62/826,612, filed on Mar. 29, 2019, which isincorporated by reference as if fully set forth.

BACKGROUND

Precision control lighting applications may require production andmanufacturing of small light-emitting diode (LED) lighting systems. Thesmaller size of such systems may require unconventional components andmanufacturing processes.

SUMMARY

Panels of LED arrays and LED lighting systems are described. A panelincludes a substrate having a top and a bottom surface. Multiplebackplanes are embedded in the substrate, each having a top and a bottomsurface. Multiple first electrically conductive structures extend atleast from the top surface of each of the backplanes to the top surfaceof the substrate. Each of multiple LED arrays is electrically coupled toat least some of the first conductive structures. Multiple secondconductive structures extend from each of the backplanes to at least thebottom surface of the substrate. At least some of the secondelectrically conductive structures are coupled to at least some of thefirst electrically conductive structures via the backplane. A thermalconductive structure is in contact with the bottom surface of each ofthe backplanes and extends to at least the bottom surface of thesubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding can be had from the following description,given by way of example in conjunction with the accompanying drawingwherein:

FIG. 1 is a top view of an example LED array;

FIG. 2 is a cross-sectional view of an example panel including multipleLED arrays;

FIG. 3 is a cross-sectional view of an example LED lighting systemincluding a singulated LED array assembly coupled to a circuit board;

FIG. 4 is a block diagram of an example circuit board to which an LEDlighting system may be attached;

FIG. 5 is a block diagram of an example wireless device in which an LEDlighting system may be incorporated;

FIG. 6 is a back view of an example wireless device;

FIG. 7 is a flow diagram of an example method of manufacturing an LEDlighting system, such as the LED lighting system of FIG. 2 ; and

FIGS. 8A, 8B, 8C, 8D, 8E, 8F, 8G, 8H, 8I, 8J and 8K are cross sectionalviews of the LED lighting system at various stages in the manufacturingprocess.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Examples of different light illumination systems and/or light emittingdiode (“LED”) implementations will be described more fully hereinafterwith reference to the accompanying drawings. These examples are notmutually exclusive, and features found in one example may be combinedwith features found in one or more other examples to achieve additionalimplementations. Accordingly, it will be understood that the examplesshown in the accompanying drawings are provided for illustrativepurposes only and they are not intended to limit the disclosure in anyway. Like numbers refer to like elements throughout.

It will be understood that, although the terms first, second, third,etc. may be used herein to describe various elements, these elementsshould not be limited by these terms. These terms may be used todistinguish one element from another. For example, a first element maybe termed a second element and a second element may be termed a firstelement without departing from the scope of the present invention. Asused herein, the term “and/or” may include any and all combinations ofone or more of the associated listed items.

It will be understood that when an element such as a layer, region, orsubstrate is referred to as being “on” or extending “onto” anotherelement, it may be directly on or extend directly onto the other elementor intervening elements may also be present. In contrast, when anelement is referred to as being “directly on” or extending “directlyonto” another element, there may be no intervening elements present. Itwill also be understood that when an element is referred to as being“connected” or “coupled” to another element, it may be directlyconnected or coupled to the other element and/or connected or coupled tothe other element via one or more intervening elements. In contrast,when an element is referred to as being “directly connected” or“directly coupled” to another element, there are no intervening elementspresent between the element and the other element. It will be understoodthat these terms are intended to encompass different orientations of theelement in addition to any orientation depicted in the figures.

Relative terms such as “below,” “above,” “upper,”, “lower,” “horizontal”or “vertical” may be used herein to describe a relationship of oneelement, layer, or region to another element, layer, or region asillustrated in the figures. It will be understood that these terms areintended to encompass different orientations of the device in additionto the orientation depicted in the figures.

Further, whether the LEDs, LED arrays, electrical components and/orelectronic components are housed on one, two or more electronics boardsmay also depend on design constraints and/or application.

Semiconductor light emitting devices (LEDs) or optical power emittingdevices, such as devices that emit ultraviolet (UV) or infrared (IR)optical power, are among the most efficient light sources currentlyavailable. These devices (hereinafter “LEDs”), may include lightemitting diodes, resonant cavity light emitting diodes, vertical cavitylaser diodes, edge emitting lasers, or the like. Due to their compactsize and lower power requirements, for example, LEDs may be attractivecandidates for many different applications. For example, they may beused as light sources (e.g., flash lights and camera flashes) forhand-held battery-powered devices, such as cameras and cell phones. Theymay also be used, for example, for automotive lighting, heads up display(HUD) lighting, horticultural lighting, street lighting, torch forvideo, general illumination (e.g., home, shop, office and studiolighting, theater/stage lighting and architectural lighting), augmentedreality (AR) lighting, virtual reality (VR) lighting, as back lights fordisplays, and IR spectroscopy. A single LED may provide light that isless bright than an incandescent light source, and, therefore,multi-junction devices or arrays of LEDs (such as monolithic LED arrays,micro LED arrays, etc.) may be used for applications where morebrightness is desired or required.

FIG. 1 is a top view of an example LED array 102. In the exampleillustrated in FIG. 1 , the LED array 102 is an array of emitters 120.LED arrays may be used for any application, such as those requiringprecision control of LED array emitters. Emitters 120 in the LED array102 may be individually addressable or may be addressable ingroups/subsets.

An exploded view of a 3×3 portion of the LED array 102 is also shown inFIG. 1 . As shown in the 3×3 portion exploded view, the LED array 102may include emitters 120 that each have a width w₁. In embodiments, thewidth w₁ may be approximately 100 μm or less (e.g., 30 μm). Lanes 122between the emitters 120 may be a width, w₂, wide. In embodiments, thewidth w₂ may be approximately 20 μm or less (e.g., 5 μm). The lanes 122may provide an air gap between adjacent emitters or may contain othermaterial. A distance di from the center of one emitter 120 to the centerof an adjacent emitter 120 may be approximately 120 μm or less (e.g., 30μm). It will be understood that the widths and distances provided hereinare examples only and that actual widths and/or dimensions may vary.

It will be understood that, although rectangular emitters arranged in asymmetric matrix are shown in FIG. 1 , emitters of any shape andarrangement may be applied to the embodiments described herein. Forexample, the LED array 102 of FIG. 1 may include over 20,000 emitters inany applicable arrangement, such as a 20×100 matrix, a symmetric matrix,a non-symmetric matrix, or the like. It will also be understood thatmultiple sets of emitters, matrixes, and/or boards may be arranged inany format to implement the embodiments described herein.

As mentioned above, LED arrays, such as the LED array 102, may includeemitters that have fine pitch and line spacing. An LED array such asthis may be referred to as a micro LED array or simply a micro LED. Amicro LED may include an array of individual emitters provided on asubstrate or may be a single silicon wafer or die divided into segmentsthat form the emitters. The latter type of micro LED may be referred toas a monolithic LED. Such arrays may pose challenges for making reliableinterconnections between individual LEDs or emitters and a circuit boardand/or other components in an LED lighting system, particularly whereeach LED or emitter is separately addressable. Additionally, such arraysmay require significant power to power them, such as 60 watts or more,and, therefore, may emit significant heat during operation. Accordingly,for such arrays, a structure is needed that can accommodate the fineline space and individual addressability of the finely spaced emittersand provide sufficient heat dissipation.

Embodiments described herein may provide for LED lighting systems,panels including a plurality of LED arrays and methods of manufacturefor LED arrays with a fine line space and may provide sufficient heatdissipation to meet the requirements of such an LED array. Such LEDarrays and LED lighting systems may be used in various applications,including, for example, camera flash applications.

FIG. 2 is a cross-sectional view of an example panel 200 includingmultiple LED arrays. In the example illustrated in FIG. 2 , the panel200 includes a substrate 212 and two LED array assemblies 202 and 204.The substrate 212 may have a top surface 210 and a bottom surface 214and may be formed from any suitable circuit board material, such as anorganic material. In embodiments, the substrate 212 may be formed from anumber of different materials, such as a core material, laminatematerials, dielectrics, solder masks and conductive materials. Each ofthe two LED array assemblies 202 and 204 may include a backplane 220embedded in the substrate 212, multiple first conductive structures 226,multiple second conductive structures 228, 229, a thermal conductor 230,an LED array 240, an underfill material 244 and wavelength convertingstructure 242. The backplane 220 may have a top surface 222 and a bottomsurface 224. The LED array 240 may be a micro LED, such as describedabove with respect to FIG. 1 .

In embodiments, for each of the LED array assemblies 202 and 204, thefirst conductive structures 226 extend from the top surface of thebackplane 220 through the substrate 212 and extend above the top surface210 of the substrate 212. In some embodiments, the first conductivestructures 226 may not extend above the top surface 210 of the substrate212 but may stop at or below the top surface 210 of the substrate 212.In some embodiments, the first conductive structures 226 may include acombination of different conductive structures. For example, the firstconductive structures 226 may include conductive vias that extendbetween the backplane 220 and the top surface 210 of the substrate 212.Conductive pillars may be disposed on and electrically coupled to theconductive vias (e.g., via metal pads on top of the conductive vias).Solder bumps may be formed on the pillars, which may be reflowed andeach coupled to an LED or emitter in an LED array. In some embodiments,a subset of the first conductive structures 216 may be electricallycoupled to the LED array. While two first conductive structures 226 areshown coupled to each backplane 220 in FIG. 2 , an array of firstconductive structures 226 may be coupled to each backplane 220 and mayhave similar line spacing to the corresponding LED array 224.

Although not shown in FIG. 2 , each of the LED arrays 240 may beelectrically coupled to corresponding second conductive structures 228,229, such as by electrical connections between the first conductivestructures 226 and the second conductive structures 228, 229 via surfacetraces, vias or other metallization in or on the backplane 220 as willbe understood to one of ordinary skill in the art. This may enableindividual LEDs or emitters in the LED arrays 240 to be individuallydriven by a driver and/or other circuitry when the panel 200 is dicedinto individual LED array assemblies 202 and 204 and mounted on acircuit board or otherwise electrically coupled to another externalassembly. In embodiments, the backplane 220 may be an interposersubstrate, which may be formed from a non-organic material. Inembodiments, the backplane 220 may be fully embedded in the substrate212 such that the substrate 212 completely surrounds the backplane 220on all sides. The backplane 220 may be formed from any of a number ofdifferent materials, including, for example organic, inorganic, siliconor glass materials.

In the example shown in FIG. 2 , the second electrical conductors 228,229 provide an electrical connection between the top surface 222 of thebackplane 220 and the bottom surface 214 of the substrate 210. Theelectrically conductive structures 228 may, for example, be conductivevias in the substrate 210. In some embodiments, the electricallyconductive structures 228 may be microvias, wires, metal pillars, soldercolumns, or other electrically conductive structures. The electricallyconductive structures 229 may, for example, be electrical traces thatextend horizontally from the backplane 220 to the electricallyconductive structures 228 and provide an electrical connectiontherebetween. As will be understood, various types and arrangements ofelectrical traces may be used, including, for example, fan-in, fan-out,linear and curved horizontal layouts. The electrically conductivestructures 228, 229 may be formed from a variety of electricallyconductive materials, including, for example, metals, such as copper,silver, aluminum, gold, or metal alloys, or conductive polymericcompositions, graphene, or conductive ceramics.

The thermal conductor 230 may be a structure of any type of thermalmaterial with good heat transfer properties, such as copper, aluminum,or other metal material. The thermal conductor 230 may be a metal slugor other rigid heat transfer plate. The thermal conductor 230 may bedisposed in a cavity in the bottom surface 214 of the substrate 210 andbe thermally coupled to the backplane 220. In the example illustrated inFIG. 2 , the thermal conductor 230 has a top surface in contact with thebackplane 220 and a bottom surface that is co-planar with the bottomsurface 214 of the substrate 212. In embodiments, however, the bottomsurface of the thermal conductor 230 may be substantially co-planar,recessed with respect to the bottom surface 214 of the substrate 212 orextend below the bottom surface 214 of the substrate 212. When the panel200 is diced, and an individual LED array assembly 202 or 204 is mountedon a circuit board, the thermal conductor 230 may be coupled to acorresponding thermal plate or other heat sink device or material, whichmay provide for the amount of heat dissipation needed for an LED array,such as described above with respect to FIG. 1 .

A wavelength converting structure 242 may be disposed over each of theLED arrays 240. In embodiments, the wavelength converting structure 242may be a phosphor material, such as a molded or ceramic materialcontaining at least one phosphor material or quantum dots or dyes. Thewavelength converting structure 242 may be any suitable thickness toprovide desired wavelength converting properties using a selectedwavelength converting material. An LED array, combined with one or morewavelength converting materials, may create white light or monochromaticlight of other colors when in an ON state. All, or only a portion of,light emitted by the LED in the ON state may be converted by thewavelength converting structure 242. Unconverted light may be part ofthe final spectrum of light emitted from the LED array assembly 202,204, though it need not be. By way of example, an LED array assembly202, 204 with a wavelength converting structure 242 may be or includeblue-emitting LEDs or emitters combined with a yellow-emitting phosphormaterial or green-emitting and red-emitting phosphor materials. By wayof another example, the LED array assembly 202, 204 with a wavelengthconverting structure 242 may be or include UV-emitting LEDs or emitterscombined with blue-emitting and yellow-emitting phosphor materials orblue-emitting, green-emitting and red-emitting phosphor materials.

The underfill material 244 may provide protection for otherwise exposedelectrical and/or electronic components and conductive elements and/orprovide or assist with mechanical coupling of the LED array 244 to thetop surface 210 of the substrate 212. In embodiments, the underfillmaterial may be a polymeric binder and may surround portions of thefirst conductive structures 226 that project above the top surface 212of the substrate 210.

LED array assemblies, such as the LED array assembly 202, 204 of FIG. 2may include additional elements (not shown), such as light absorbers,reflectors, other optical coatings, or electrically insulating material.In embodiments, an LED array assembly may include an optically andelectrically insulating material, such as organic, inorganic or acombination organic/inorganic binder or filler material. For example,adhesives, epoxies, acrylate or nitrocellulose may be used inconjunction with ceramic particles to provide the underfill 244. Anotherorganic/inorganic binder, filler or sidewall may be, for example, anepoxy with embedded reflective titanium oxide or other reflectivescattering particles. Inorganic binders may include sol-gel (e.g., asol-gel of TEOS or MTMS) or liquid glass (e.g., sodium silicate orpotassium silicate), also known as water glass. In embodiments, bindersmay include fillers that adjust physical properties. Fillers may includeinorganic nanoparticles, silica, glass particles or fibers or othermaterials capable of improving optical or thermal performance.

In embodiments, microlenses or other primary or secondary opticalelements, such as reflectors, scattering elements or absorbers, may becoupled or positioned with respect to each LED or emitter or associatedwavelength converting structure. Additionally or alternatively, aprimary optic may be positioned over the entire LED array, which may bedirectly attached or mounted at a distance from the LED array insuitable packaging. Protective layers, transparent layers, thermallayers or other packaging structures may be used, as needed, forspecific applications.

FIG. 3 is a cross-sectional view of an example LED lighting systemincluding a singulated LED array assembly 202 coupled to a circuit board300. In the example illustrated in FIG. 3 , the bottom surface 214 ofthe substrate 212 is placed adjacent a top surface of the circuit board300. The circuit board may have a number of conductive pads 302. In theexample illustrated in FIG. 3 , the conductive pads 302 on the circuitboard 300 are soldered or otherwise electrically coupled to the secondconductive structures 229. The thermally conductive structure 230 in thesubstrate 212 may also be soldered, placed in contact with or otherwisethermally coupled to a thermally conductive pad 304 on the circuitboard. The direct contact and/or bond between the thermally conductivestructure 230 and the circuit board 300 enables efficient heat transferfrom the LED assembly 202 to the circuit board 300 for heat sinkingpurposes without need for additional heat dissipating structures overthe top of the LED lighting system (or elsewhere) that may, for example,otherwise block light emission from the LED array 240. The circuit board300 may be part of a larger system used in specific applications(examples are described below with respect to FIGS. 4, 5 and 6 ). Sincethe second conductive structures 229 are electrically coupled with thefirst conductive structures 226, the LED array 202 may be electricallycoupled to the circuit board 300 for powering, driving or otherwisecontrolling optical emission from the LED array 202 via circuitry on thecircuit board 300.

As mentioned above, LED arrays, such as the LED arrays 202, 204, may beaddressable assemblies and may support applications that benefit fromfine-grained intensity, spatial, and temporal control of lightdistribution. This may include, but not be limited to, precise spatialpatterning of emitted light from pixel blocks or individual pixels.Depending on the application, emitted light may be spectrally distinct,adaptive over time, and/or environmentally responsive. The LED arraysmay provide pre-programmed light distribution in various intensity,spatial or temporal patterns. The emitted light may be based at least inpart on received sensor data and may be used for optical wirelesscommunications. Associated optics may be distinct in a pixel, pixelblock, or device level. An example LED array may include a device havinga commonly controlled central block of high density pixels with anassociated common optic, whereas edge pixels may have individual optics.Common applications supported by LED arrays may include camera flashes,automotive headlights, architectural and area illumination, streetlighting, and informational displays.

FIG. 4 is a top view of an example circuit board 300 that includes anLED device attachment region 418 for attachment of an LED arrayassembly, such as LED array assemblies 202, 204. In the exampleillustrated in FIG. 4 , the circuit board 300 includes a power module412, a sensor module 414, and a connectivity and control module 418 on asubstrate.

The sensor module 414 may include sensors needed for an application inwhich the LED array is to be implemented. Example sensors may includeoptical sensors (e.g., IR sensors and image sensors), motion sensors,thermal sensors, mechanical sensors, proximity sensors, or even timers.By way of example, LEDs in street lighting, general illumination, andhorticultural lighting applications may be turned off/on and/or adjustedbased on a number of different sensor inputs, such as a detectedpresence of a user, detected ambient lighting conditions, detectedweather conditions, or based on time of day/night. This may include, forexample, adjusting the intensity of light output, the shape of lightoutput, the color of light output, and/or turning the lights on or offto conserve energy. For ARNR applications, motion sensors may be used todetect user movement. The motion sensors themselves may be LEDs, such asIR detector LEDs. By way of another example, for camera flashapplications, image and/or other optical sensors or pixels may be usedto measure lighting for a scene to be captured so that the flashlighting color, intensity illumination pattern, and/or shape may beoptimally calibrated. In alternative embodiments, the circuit board 300does not include a sensor module.

The connectivity and control module 416 may include the systemmicrocontroller and any type of wired or wireless module configured toreceive a control input from an external device. By way of example, awireless module may include blue tooth, Zigbee, Z-wave, mesh, WiFi, nearfield communication (NFC) and/or peer to peer modules. Themicrocontroller may be any type of special purpose computer or processorthat may be embedded in an LED lighting system and configured orconfigurable to receive inputs from the wired or wireless module orother modules, devices or systems in the LED lighting system (such assensor data and data fed back from an LED array attached at the LEDdevice attach region 418) and provide control signals to other modulesbased thereon. Algorithms implemented by the special purpose processormay be implemented in a computer program, software, or firmwareincorporated in a non-transitory computer-readable storage medium forexecution by the special purpose processor. Examples of non-transitorycomputer-readable storage mediums include a read only memory (ROM), arandom access memory (RAM), a register, cache memory, and semiconductormemory devices. The memory may be included as part of themicrocontroller or may be implemented elsewhere, either on or off thecircuit board 300.

The term module, as used herein, may refer to electrical and/orelectronic components disposed on individual circuit boards that may besoldered to one or more circuit boards 300. The term module may,however, also refer to electrical and/or electronic components thatprovide similar functionality, but which may be individually soldered toone or more circuit boards in a same region or in different regions.While the circuit board 300 is illustrated in FIG. 4 as having certainmodules, these are for illustration and example only. One of ordinaryskill in the art will recognize that a circuit board may include anynumber and variety of different modules depending on the application.

As mentioned above, an LED lighting system, such as illustrated in FIG.3 , may be used in a number of different applications, and may beparticularly useful in flash applications where closely packed LEDarrays and/or individually addressable LED devices or emitters may bedesirable. FIGS. 5 and 6 are diagrams of example application systemsthat may incorporate LED lighting systems, such as the LED lightingsystem 300 of FIG. 3 . The examples illustrated in FIGS. 5 and 6 are foran LED flash application, although one of ordinary skill in the art willunderstand that LED array assemblies, such as described herein, may beused for many different applications.

An LED array may be well suited for camera flash applications for mobiledevices. Typically, an intense brief flash of light from a highintensity LED may be used to support image capture. Unfortunately, withconventional LED flashes, much of the light is wasted on illumination ofareas that are already well lit or that do not otherwise need to beilluminated. Use of a light emitting pixel array may provide controlledillumination of portions of a scene for a determined amount of time.This may allow the camera flash to, for example, illuminate only thoseareas imaged during rolling shutter capture, provide even lighting thatminimizes signal to noise ratios across a captured image and minimizesshadows on or across a person or target subject, and/or provide highcontrast lighting that accentuates shadows. If emitters of the LED arrayare spectrally distinct, color temperature of the flash lighting may bedynamically adjusted to provide wanted color tones or warmth.

FIG. 5 is a diagram of an example wireless device 500. In the exampleillustrated in FIG. 5 , the wireless device 500 includes a processor512, a transceiver 502, an antenna 504, a speaker/microphone 506, akeypad 508, a display/touchpad 510, a memory 516, a power source 518,and a camera 514.

The processor 512 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), amicroprocessor, one or more microprocessors in association with a DSPcore, a controller, a microcontroller, an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA)circuit, an integrated circuit (IC), a state machine, and the like. Theprocessor 512 may be coupled to, and may receive user input data from,the speaker/microphone 506, the keypad 508, the display/touchpad 510and/or the camera 514. The processor 512 may also output user data tothe speaker/microphone 506, the keypad 508, the display/touchpad 510and/or the camera 514. In addition, the processor 512 may accessinformation from, and store data in, any type of suitable memory, suchas the memory 516. The processor 512 may receive power from the powersource 518 and may be configured to distribute and/or control the powerto the other components in the wireless device 500.

The processor 512 may also be coupled to the camera 514. In embodiments,the camera 514 may include, for example, an image sensor, read outcircuitry, a flash module and/or any other required circuitry orcontrols required to operate the camera 514. In embodiments, the flashmodule may include an LED lighting system, such as the LED lightingsystem 300 of FIG. 3 , and a driver, one or more sensors and/or anyother circuitry or controls required to operate the flash.

FIG. 6 is a back view of a wireless device 600 showing more detail ofthe camera 514. In the example illustrated in FIG. 6 , the wirelessdevice 600 includes a casing 620 and a camera 514. The camera 514includes a lens 640 via which the camera's image sensor (not shown inFIG. 6 ) may capture an image of a scene. The camera module 514 may alsoinclude a flash 650 that may include one or more LED arrays, which maybe a part of one or more LED lighting systems, such the LED lightingsystem 300 of FIG. 3 .

FIG. 7 is a flow diagram of an example method 700 of manufacturing apanel of LED arrays and/or an LED lighting system, such as the panel 200of FIG. 2 and/or the LED lighting system 300 of FIG. 3 . FIGS. 8A, 8B,8C, 8D, 8E, 8F, 8G, 8H, 8I, 8J and 8K are cross sectional views of apanel of LED arrays at various stages in the manufacturing method.

In the example method 700 illustrated in FIG. 7 , a cavity is formed ina substrate (702). FIG. 8A is a cross-sectional view 800A of thesubstrate 802. The substrate 802 has vias 803 formed therein andmetallization 804 formed over portions of the top and bottom surfaces ofthe substrate 802 and in the vias 803. The metallization 804 form atleast portions of the second conductive structures 228, 229 of FIG. 2 .FIG. 8B is a cross-sectional view 800B of the substrate 802 with acavity 806 formed therein. While the opening is shown in thecross-sectional view as completely separating the substrate 806 into twopieces, the cavity may be formed partially through the substrate or maybe a via or other opening formed completely through the substrate butsurrounded on all sides by at least a portion of the substrate 802.

Referring back to FIG. 7 , a backplane may be placed in the cavity inthe substrate (704). FIGS. 8C and 8D are cross-sectional views 800C and800D of the substrate at different points in the placing of thebackplane. In FIG. 8C, a tape 808 or other temporary structure is placedover the substrate 802 and adhered or otherwise coupled to a top surface810 of the metallization 804. In FIG. 8D, a backplane 812 is placed inthe cavity 806 and adhered or otherwise coupled to the tape or othertemporary structure 808.

Referring back to FIG. 7 , at least one layer of a dielectric materialmay be formed over the substrate and the backplane (706). FIGS. 8E and8F are cross-sectional views 800E and 800F of the substrate at variouspoints during the formation of the at least one layer of the dielectricmaterial. FIG. 8E is a cross-sectional view showing dielectric material814 formed over one side of the backplane 812 and the substrate 802while the other side of the backplane 812 and the substrate 802 arestill on the tape or other temporary structure 808. In the exampleillustrated in FIG. 8E, the dielectric material 814 also fills all voidsand vias within the substrate 802 that are not filled with anothermaterial. In FIG. 8F, the tape or other temporary structure 808 isremoved, and at least one other layer of the dielectric material 814 isformed on the side of the substrate 802 and the backplane 812 exposed bythe removal of the tape of other temporary structure 808. Inembodiments, the dielectric material may be a polymer dielectricmaterial, such as polyimide.

The at least one layer of dielectric material 814 may be one or moreredistribution layers (RDL). The number of RDL layers may depend on thespecific application for which the LED array panel is being implemented.Relative to the panel 200 of FIG. 2 , the substrate 802, along with atleast portions of the dielectric material 814, may form the substrate212 of FIG. 2 in which the backplane 220 is embedded. In other words,one method of embedding the backplane 220 in the substrate 212 mayinclude forming a cavity in a substrate, such as the substrate 802, andthen forming one or more layers of dielectric over the substrate and thebackplane such that the backplane is embedded in the substrate alongwith the at least one layer of dielectric material.

Referring back to FIG. 7 , a cavity may be formed in the at least onelayer of dielectric material, exposing at least a portion of a surfaceof the backplane (708). A heat conductive material is placed in the atleast one layer of dielectric material (710). Referring back to FIG. 8F,a cavity is formed in the dielectric material 814, and the heatconductive material 818 is placed in the cavity.

FIG. 8G is a cross-sectional view 800G of the panel. In FIG. 8G, theentire assembly of FIG. 8F has been flipped, and vias have been formedin what is now the top surface of the dielectric material 814 andexposing a surface of the backplane 812. The vias may be filled or linedwith a conductive material, and conductive pads 816 may be formed on anouter surface of the dielectric material 814. The vias (and optionallythe pads) with the conductive material may form the first conductivestructures 226 of FIG. 2 , for example. Other vias and optionallyconductive pads 816 may be formed in what is now the bottom surface ofthe dielectric material 814. These may be electrically coupled to themetallization 804 and may be part of the second conductive structures228, 229 of FIG. 2 , which extend to the bottom surface of the substrate212. Although not shown in FIG. 8G, these portions of the vias/pads 816formed in the bottom surface of the dielectric material 814 and themetallization 804 may be electrically coupled to the vias/pads 816formed in the top surface of the dielectric material 814 by tracesand/or vias in or on the backplane 812 or by other portions of themetallization 804 or conductive materials lining or filling the vias, asexplained above with respect to FIG. 2 . This may provide an electricalcoupling between the first conductive structures 226 and the secondconductive structures 228, 229, as described above. While only threevias/pads 816 are shown extending from the top surface of the backplane812 in FIG. 8G, there may be an array of closely spaced vias/pads, whichmay be electrically coupled to individual LED or emitters in the LEDarray.

FIGS. 8H, 8I, 8J, and 8K are diagrams of examples 800H, 800I, 800J and800K of the panel at various additional stages in the method. In FIG.8H, a solder mask or other passivation material 820 may be formed oncertain portions of top and bottom surfaces of the dielectric material814. In FIG. 8I, conductive pillars 822, such as copper pillars, may beformed on the conductive pads 816 of FIG. 8G. In FIG. 8J, soldermaterial 824, such a solder bumps or balls, may be formed on theconductive pillars 822. In FIG. 8K, an LED array 826 may be placed orotherwise disposed over the solder material 822. The entire assembly800K may be heated, and the solder material 822 may reflow, thuselectrically and mechanically coupling the LED array 826 to the pillars822. The pillars 822 may be coupled to individual LEDs or emitters inthe LED array 826. Although not shown, subsequent processing steps maybe performed, including forming the underfill, forming the wavelengthconverting structure over the LED array 826 (e.g., phosphorintegration), substrate thinning or laser liftoff (e.g., thinning orremoval of any growth or other temporary substrate of the LED array 826)and/or dicing the panel into multiple LED lighting systems, such as theLED lighting system 300 of FIG. 3 .

In embodiments, the wavelength converting structure may be formed byelectrophoretically depositing a material containing at least onephosphor material with application of a voltage. Varying an appliedvoltage duration may correspondingly vary an amount and thickness of thedeposited material. Alternatively, the LED may be coated with thephosphor-containing material, for example using an organic binder toadhere phosphor particles to the LED array. Phosphor-containingmaterials may be dispensed, screen printed, sprayed, molded orlaminated. Alternatively, for certain applications. Glass containing atleast one phosphor material and/or a pre-formed sintered ceramiccontaining a phosphor material may be coupled to the LED array.

While the Figures described above show the thermally conductivematerial, the LED array and the backplane having certain relative sizes,one of ordinary skill in the art will recognize that the sizes of theseelements may vary. For example, the backplane may be larger or smallerthan the corresponding LED array, and the thermally conductive materialmay be larger or smaller than the backplane. The sizes of each of theseelements may depend, for example, on performance and cost optimization.

Having described the embodiments in detail, those skilled in the artwill appreciate that, given the present description, modifications maybe made to the embodiments described herein without departing from thespirit of the inventive concept. Therefore, it is not intended that thescope of the invention be limited to the specific embodimentsillustrated and described.

What is claimed is:
 1. A panel of light-emitting diode (LED) arrays, thepanel comprising: a substrate having a top surface and a bottom surface;a plurality of backplanes embedded in the substrate, each of theplurality of backplanes having a top surface and a bottom surface; aplurality of arrays of first electrically conductive structuresextending at least from the top surface of each of the plurality ofbackplanes to the top surface of the substrate; a plurality of LEDarrays, each electrically coupled to one of the plurality of arrays offirst electrically conductive structures; a plurality of secondelectrically conductive structures extending from each of the pluralityof backplanes to at least the bottom surface of the substrate, at leastsome of the second electrically conductive structures electricallycoupled to at least one of the plurality of LED arrays; and a pluralityof thermal conductors, at least one of the plurality of thermalconductors in contact with the bottom surface of one of the plurality ofbackplanes and extending to at least the bottom surface of thesubstrate.